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N PETERS. 0T=UTNOGRAPHEFL WASHINGTON. D. C.

UNITED STATES PATENT OFFICE.

JOSEPH B. MATTHEWS, OF BALTIMORE, MARYLAND, ASSIGNOR OF ONE- HALF TO WILLIAM K. MILLHOLLAND, OF SAME PLACE.

BALANCED SLIDE-VALVE.

SPECIFICATION formingpart of Letters Patent No. 236,901, dated January 25, 1881.

Application filed April 2'7, 1880. (N model.)

To all whom it may concern:

Be it known that I, JOSEPH B. MATTHEWS, of Baltimore city, State of Maryland, have invented certain new and useful Improvements in Balanced Slide-Valves; and I hereby declare the same to be fully, clearly, and exactly described as follows, reference being had to the accompanying drawings, in which- Figure 1 is a central longitudinal sectional view of the device. Fig. 2,is a transverse sectional view on line X X of Fig. 1; and Fig. 3 is a plan view of one of the heads of the valve.

My invention has reference to balanced slide-valves for steam-cylinders; and it consists in a valve constructed as hereinafter set forth, whereby it is perfectly balanced longitudinally as well as laterally.

In the accompanying drawings, A is the valve-casing, adapted to be bolted, as usual, to the cylinder within the steam-chest, and having inlet and exhaust ports 0 D, as shown. Opposite the ports the casin g is chambered, as shown at H H, so that a space is left all around the valve as it passes the ports, allowing the live steam to press evenly on the periphery of the valve. The latter,consists of a pair of disks, B B, connected by a rod, I. The disk or head B, to which the valve-stem E is attached, is made larger than the head B, the difference being equal to the cross-section of the stem E, so that the valve is perfectly balanced with reference to its longitudinal motion, the steam-pressure on the heads being equalized.

Now, inasmuch as some difficulty would attend the attachment of the device to the cylinders of engines already in use, by reason of the time and labor lost in securing absolute accuracy of registration of the axis of the stem with that of the valve, I make use of a means for connecting the parts whereby this difliculty is wholly obviated, and no necessity exists for making the axes of stem and valve register at all. These means are shown in Figs. 1 and 3 of the drawings. The head B is chambered out, as shown at G, an undercut recess being made to surround a central orifice. A disk, F, of a size to pass through this orifice is attached to the stem E, and being made to enter the orifice, occupies a position, when entered, more or less eccentric, as shown in Fig. 3. This feature, furthermore, enables one to alter the throw of the valve-stem with great facility, by reason of the fact that the free rotation of the stem with reference to the valve is admitted of.

The valve is in every sense a truly-balanced valve, the spaces H around the valve allowing the steam to press evenly upon the periphery of the same, and the difference in area of the heads balancing it longitudinally.

The device is adapted for attachment to cylinders of engines already in use, it being only necessary to secure the casin g by means of screw-boltsinserted through the lateral flange.

I do not claim the means of attaching the valve-stem to the valve, as such is not my invention.

What I claim is- In a balanced slide-valve, a casing having grooves or recesses opposite the ports, as described, and containing a double piston-valve whose heads differin area, the said difference being equal to the cross-sectional area of the valve-stem, whereby the valve is balanced longitudinally and laterally, as set forth.

JOSEPH B. MATTHEWS.

Witnesses:

R. D. WILLIAMS, W. K. MILHOLLAND. 

